The WLTP: How a new test procedure for cars will affect fuel consumption values in the EU

The current European type-approval procedure for fuel consumption and CO2 emissions of cars (the New European Driving Cycle, or NEDC) includes a number of tolerances and flexibilities and no longer accurately reflects state-of-the-art technologies. The European Union is planning to replace it with the newly developed Worldwide Harmonized Light Vehicles Test Procedure in 2017.

The WLTP deviates in some details from the NEDC, which will affect the determination of the official EU type-approval emission values. This also has consequences for the NEDC-based CO2 passenger cars’ emission target for 2020/2021 (95 g CO2/km), which will have to be adapted to the new testing procedure.

This paper identifies the main influencing parameters and quantifies their impacts. The effects of the new driving cycle and the new definition of the vehicles’ test masses result in a new WLTP-based target of 100 g CO2/km for 2020. If the ambient test temperature is also changed for the EU-WLTP (to 14 °C instead of 23 °C), an additional correction of 2 g CO2/km would be appropriate, making the target 102 g CO2/km.